Information AboutPumicite |
| CATEGORIES ABOUT PUMICE | |
| igneous rocks | |
| volcanology | |
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Pumice is a light, porous type of Pyroclastic Igneous Rock . It is formed during explosive Volcanic eruptions when liquid Lava is ejected into the air as a froth containing masses of gas bubbles. As the lava solidifies, the bubbles are frozen into the rock. Any type of igneous rock — Andesite , Basalt , Dacite or Rhyolite — can form pumice given suitable eruptive conditions. When larger amounts of gas are present, the result is a finer-grained variety of pumice known as '''pumicite'''. It is considered a Glass because it has no Crystal Structure . Pumice varies in density according to the thickness of the solid material between the bubbles; many samples float in Water . Pumice comes in many different colors such as white, yellowish, grey, grey brown, and a dull red. It is widely used to make lightweight Concrete and as an Abrasive , especially in polishes and Cosmetics exfoliants. When used as an additive for Cement , a fine-grained version of pumice called Pozzolan is mixed with Lime to form a light-weight, smooth, plaster-like Concrete . This form of concrete was used as far back as Roman times. |
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